Vegetation change in semi-permanent or ephemeral montane marshes (lagoons) of the New England Tablelands Bioregion

Abstract

The vegetation communities within semi-permanent or ephemeral montane marshes colloquially known as lagoons are an under investigated wetland type of the New England Tablelands Bioregion (NETB) yet they are listed (Upland Wetlands) on both state and federal acts as endangered. Lack of survey and analysis of plot data has meant that the variation in vegetation due to zonation, seasonality and unpredictable wetting and drying cycles are poorly understood. Here, 317 full floristic 2 × 2-m plots were placed across 13 lagoons. The plot data were classified to allow description of native and novel vegetation types using the hierarchical EcoVeg schema. The updated classification includes one Division and Macrogroup with 15 Alliances and 47 Associations. Permanent 50-m transects with a 1 × 1-m plot at every 5m (10 per transect) were placed within lagoons. Five lagoons were resurveyed annually for 3years. Within transects, each plot was assigned an Association after each survey period. Approximately one third of transect plots changed in vegetation type each year, often at the Alliance level. Over the 3-year period the number of Associations reduced by ~30% across transects associated with increasing drought and drying out of the wetlands. Transitional environments with the greatest level of hydrological periodicity had the greatest variety of Associations recorded. Highly dynamic systems with increased temporal turnover are likely to require increased sampling effort both spatially and temporally than more stable vegetated systems. The constant changing nature of these communities poses significant issues for management and conservation planning, including benchmarking and offsetting, which may require novel solutions.

Australian advances in vegetation classification and the need for a national, science-based approach

“…Specifically, in Australia, climate and available energy operate broadly, whereas topography, soils and fire (and other disturbances, e.g. cyclones) act at intermediate scales (Havel 1975;Hunter 2021a). The role of nutrient poverty and fire (Milewski 1983;Orians and Milewski 2007); old v. young landscapes and climatic 'stability' (Hopper 2009;Mucina and Wardell-Johnson 2011;Hopper et al 2021) and alternative stable states (Peterson 1984;Sousa and Connell 1985;Pausas and Dantas 2017) are important, as is the role of competition and top down effects (e.g.…”

“…Bell and Driscoll (2021) outline a new method (data-informed sampling and mapping: D-iSM) for vegetation mapping that ensures that plot-based classifications identify rare and restricted vegetation types. Hunter (2021aHunter ( , 2021b highlights the importance of the temporal dimension in defining communities sensitive to inter-annual variation, e.g. ephemeral montane marshes (lagoons) or ephemeral vegetation types associated with the aseasonal climates found in the arid and semi-arid zone.…”

Poplar box woodlands of Eastern Australia: an assessment of a threatened ecological community within the IVC framework

“…However, this necessarily requires that such communities are defined and are identifiable. Without clear definitions of inclusion or exclusion we risk conservation priorities being misdirected (Hunter 2021a;Saunders et al 2021).…”

“…Potential listings are then refined and placed on public exhibition for comment before finally being presented to the federal minister for acceptance or rejection. Although guidelines suggest that communities should be defined based on numerical classification this has not been applied to many currently listed, some of which are clearly defined based on geomorphological features with only a generalised concept of a floristic assemblage (see, e.g., Hunter and Hunter 2020;Hunter 2021a). Without a full comprehen-sion of all floristic and ecological components and interrelationships with co-occurring types, a real understanding cannot be gained of threats and persistence (Franklin et al 2016;Jansen et al 2016).…”

“…Several tests have been completed within select vegetation types (e.g. Hunter and Lechner 2017;Addicott et al 2018;Hunter 2020;Hunter and Hunter 2021a;Muldavin et al 2021). Here we introduce an additional test based on the Poplar Box Woodland dominated by Eucalyptus populnea.…”